Depth of field is one of the most important elements of photography. For most of your captures, you’ll need to more or less consciously control depth of field. You probably already know that aperture is the way to do that. You may also know that it is not the only tool at your disposal. This post will briefly summarize the art of controlling depth of field, then I’ll discuss some of the factors you should consider when choosing depth of field for your images.
What is depth of field? A good working definition goes like this: The extent to which parts of an image are in focus from front (near the camera) to back (far away) is that image’s depth of field. As you can see it is rather subjective.
Depth of field is often confused with depth, which I posted on awhile back. Giving your images a sense of depth, though related to depth of field, is quite different. Depth is the degree to which you foster the illusion of three dimensions in your two-dimensional pictures. A photograph with good sense of depth, for example, can have a depth of field that is shallow, deep or somewhere in between.
Control depth of field in your images using one or a combination of the following methods:
- Aperture: Small apertures (big f/numbers) yield greater depth of field, where more of the scene is in clear focus. Large apertures (small f/numbers) give shallow depth of field, where just your subject is in clear focus.
- Focal Length: The longer the focal length you use, the shallower your depth of field will be. A short focal length (wide angle)will give yield greater depth of field.
- Relative distance: To get greater depth of field, increase the distance from you to the closest thing you want in focus. To get shallower depth of field, simply move closer to your subject. That’s the simple way to explain it. Really what you want to do is change the relative distance between you and the subject as compared with the distance between the subject and background. For greater depth of field increase this relative distance. For shallower depth of field decrease the relative distance. See the example images below.
- The right lens: It may not seem so, but a particular lens’s characteristics can lean the images it produces toward greater or lesser depth of field. This is a minor factor compared with the others, but it’s real. I’m not talking about lenses with large maximum apertures (“fast” with low f/number designations), in order to achieve shallow depth of field. That’s all about factor #1 above.
I’m talking about how some wide-angle lenses allow you to photograph scenes where all is in focus, even if elements are both very close and far away. And how other lenses tend to yield an especially smooth out of focus background, or nicer-looking bokeh (out of focus highlights). Tilt-shift lenses are a somewhat extreme example of lens build influencing focus characteristics. And of course macro lenses have much shallower depths of field than other lenses do (see images below).
This will get us going on the discussion. Please let me know if you have anything to add or any questions. And if you’re interested in any of my images, whether on here or on my main gallery page, please let me know by contacting me. I would be happy to honor any request no matter how unusual. Stay tuned for more on depth of field. Thanks for reading and have a great week!